02-04-2012Karoo radio telescope reaches another milestone

South Africa’s Karoo-based KAT-7 radio telescope array has made a major step in its transition from being an engineering prototype to an operational instrument. The seven-dish array has successfully observed radio emissions from neutral hydrogen gas in the NGC 3109 galaxy, which is located some 4.3-million light years from earth.

“Our team in the SKA South Africa project and universities has again shown that they can deliver cutting-edge technology and do excellent science on a very tight schedule" enthuses SKA South Africa director Dr Bernie Fanaroff.

Neutral hydrogen gas radio emissions have an exact frequency of 1 420 MHz. Those from NGC 3109 were processed in KAT-7’s correlator, which currently can determine the velocity of the gas to an accuracy of 10 km/s, but, by the end of this year, will have been upgraded to achieve an accuracy of 1 km/s.

“A large proportion of the science planned for the SKA – and MeerKAT – involves [the] mapping of the universe using neutral hydrogen,” explains Fanaroff. “Because of the ongoing expansion of the universe, distant galaxies are moving away from us. Measuring the frequency of the spectral line from neutral hydrogen in those galaxies allows us to work out how far away they are. By finding billions of distant galaxies, astronomers will be able to map the structure of the universe and how it has changed over time. This cosmic census of the neutral hydrogen in galaxies – far and near – is essential in understanding the deeper physics of the universe, by answering fundamental questions such as the nature of dark matter and dark energy.”

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